I. Field of the Invention
The present invention relates generally to fuel systems for engines and, more particularly, to an electrically controlled fuel metering system.
II. Description of the Prior Art
In fuel delivery systems for internal combustion engines, and particularly aircraft engines, fuel is typically pumped from a fuel reservoir or tank to an inlet port on a fuel metering device. The fuel metering device includes an outlet port which is fluidly connected to the engine and a fuel return port which is fluidly connected to the fuel reservoir. A valve assembly contained within the fuel metering device variably fluidly connects the inlet port to the outlet and return ports in accordance with the fuel demanded by the engine operator. Thus, if additional fuel to the engine were required, the fuel metering device diverts a proportionately greater amoumt of fuel from its inlet port to the outlet port and less to its return port, and vice versa.
One disadvantage of these previously known fuel metering devices, however, is that the valve is controlled by a mechanical linkage extending from the engine operator and to the fuel metering device. This is disadvantageous in several different respects. First, the mechanical linkage increases the weight of the overall fuel system. This is particularly disadvantageous in weight critical applications, such as aircraft engines. Furthermore, the mechanical linkage requires periodic maintainance and inspection and is prone to failure.
A still further disadvantage of these previously known mechanically actuated fuel metering devices is that such devices require physical actuation by the engine operator. As such, these previously known devices are not easily adaptable to automated fuel delivery systems.